#include <stdlib.h> 
#include <stdio.h> 

int sum(int a, int b) {
    return a + b;
}

void fun(int* a, int* b, int (*sum)(int ,int))
{
    *a = 5;
    printf("%d+%d=%d\n", *a, *b, sum(*a, *b));
}

int main(void)
{
    void (*p)(int*, int*, int (*)(int, int));
    p = &fun;
    int a = 1, b = 2;
    p(&a, &b, &sum);
    printf("a = %d\n",a);
    return 0;
}

